Bicycle hub

1. A bicycle hub comprising:

a hub axle defining a rotational axis;

a hub shell rotatably mounted on the hub axle to rotate around the rotational axis;

a sprocket support body rotatably mounted on the hub axle to rotate around the rotational axis, the sprocket support body having an outer peripheral surface with a first helical spline;

a first ratchet member having at least one first ratchet tooth and a second helical spline mating with the first helical spline; and

a second ratchet member having at least one second ratchet tooth mating with the at least one first ratchet tooth and a hub shell engagement portion that engages the hub shell,

the outer peripheral surface of the sprocket support body having a guiding portion configured to guide the first ratchet member toward the hub shell while coasting, the guiding portion arranged to define an obtuse angle with the first helical spline.

2. The bicycle hub according to claim 1 , wherein

the at least one first ratchet tooth is disposed on an axial facing surface of the first ratchet member, and

the at least one second ratchet tooth is disposed on an axial facing surface of the second ratchet member that faces the axial facing surface of the first ratchet member.

3. The bicycle hub according to claim 1 , wherein

the first ratchet member is movably mounted in an axial direction with respect to the sprocket support body via the second helical spline engaging the first helical spline while driving by a first thrust force is applied from the sprocket support body.

4. The bicycle hub according to claim 1 , wherein

the at least one second ratchet tooth mates with the at least one first ratchet tooth to transfer torque from the sprocket support body to the hub shell.

5. The bicycle hub according to claim 1 , wherein

the guiding portion is configured so as to release a meshing engagement between the at least one first ratchet tooth and the at least one second ratchet tooth while coasting.

6. The bicycle hub according to claim 1 , wherein

the guiding portion extends in at least a circumferential direction with respect to the sprocket support body.

7. The bicycle hub according to claim 1 , wherein

the second ratchet member transfers torque to the hub shell applied from the first ratchet member via the hub shell engagement portion.

8. The bicycle hub according to claim 1 , wherein

one of the hub shell engagement portion and the hub shell includes at least one protrusion extending radially and the other of the hub shell engagement portion and the hub shell includes at least one recess that is engaged with the at least one protrusion.

9. The bicycle hub according to claim 1 , further comprising

a biasing member disposed between the hub shell and the first ratchet member, the biasing member biasing the first ratchet member in the axial direction toward the second ratchet member.

10. The bicycle hub according to claim 1 , wherein

the biasing member is configured to rotate with the hub shell, and

the first ratchet member contacts the guiding portion and disengages from the second ratchet member by a second thrust force caused by friction torque between the biasing member and the first ratchet member while coasting.

11. The bicycle hub according to claim 1 , further comprising

a cover member covering an annular gap between the sprocket support body and the hub shell.

12. The bicycle hub according to claim 1 , further comprising

at least one bearing assembly rotatably supporting the sprocket support body on the hub axle.

13. The bicycle hub according to claim 1 , further comprising

at least one bearing assembly rotatably supporting the hub shell on the hub axle.

14. The bicycle hub according to claim 1 , wherein

the at least one first ratchet tooth includes a plurality of first ratchet teeth, and

the at least one second ratchet tooth includes a plurality of second ratchet teeth.

15. The bicycle hub according to claim 1 , wherein

the sprocket support body includes a plurality of additional helical splines on the outer peripheral surface, and

the first ratchet member includes a plurality of additional helical splines in mating engagement with the additional helical splines of the sprocket support body.

16. The bicycle hub according to claim 1 , wherein

the first and second ratchet members are annular members.

17. The bicycle hub according to claim 16 , wherein

the sprocket support body includes an abutment that abuts the second ratchet member to restrict axial movement of the second ratchet member away from the hub shell, and

the first ratchet member is disposed on an axial side of the second ratchet member that is opposite to the abutment of the sprocket support body.

18. The bicycle hub according to claim 17 , further comprising

a biasing member disposed between the hub shell and the first ratchet member, the biasing member biasing the first ratchet member in the axial direction toward the second ratchet member.

19. The bicycle hub according to claim 18 , wherein

the hub shell includes an internal space,

the outer peripheral surface of the sprocket support body supports the first and second ratchet members, and

each of the ratchet support body, the biasing member and the first and second ratchet members being at least partially disposed in the internal space of the hub shell.

20. The bicycle hub according to claim 19 , further comprising

a cover member covering the internal space between the sprocket support body and the hub shell.